DNA

When the statistical observations of Gregor Mendel were compared with what could be seen under the microscope, it became clear that the hereditary material resided in chromosomes. Mendel observed that “factors” (that is, genes) occur in pairs, one member from each parent. The microscope revealed that chromosomes occur in pairs, one member from each parent. Mendel observed that when reproductive cells are produced, the factors separate and are distributed as units (the laws of segregation and unit characters). The microscope showed that in meiosis, the homologous chromosomes separate, with only one of each. pair going to a gamete. Mendel noted that in a dihybrid, the distribution of one pair of factors is independent of the distribution of the other (the law of independent assortment). The microscope showed that in meiosis, the distribution of maternal and paternal chromosomes is random. The evidence that the hereditary material resides in chromosomes was undeniable.